| Abstract
| - Ketonic defects have been identified as the origin of green-shifted emission in bridged poly(p-phenylene) (PPP) type materials. In this contribution, we present a joint experimental and quantum-chemical study to discuss the impact of ketonic defects on the optical and infrared properties of fully bridged ladder-type PPP.
- We investigate the oxidative degradation process occurring in ladder-type poly(p-phenylene)(LPPP) by spectroscopic and quantum-chemical techniques. Annealing experiments carriedout for two representatives of the class of LPPP's with different side chains relate the changein emissive behavior of the polymer to the presence of ketonic defects on the main chain.The geometry, excitation, and emission energies as well as vibrational modes are calculatedfor model LPPP oligomers bearing these defects. The optical properties of these moleculesare significantly changed compared to the pristine model systems. In the excited-stategeometry, ketone-containing oligomers possess emissive excited states in the energy regionof the experimentally observed low-energy emission band. The calculated infrared (IR)absorption peaks associated with the defects can also be correlated with the experimentalIR spectra.
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